Plug a weeding tool into a long extension cord or cords that will allow you to reach the entire length of the fence. If you are using a gas-powered weeding tool, ensure it has enough gasoline in the tank, and pull the starter cord to engage the motor.
Start at one end of the fence and work your way across the length of the fence. Hold the weeding tool by its handle, waist-high in front of your body. Tilt the tool slightly so the head with the cutting line is at an angle to the weeds.
Move the weeding tool back and forth along the base of the weeds in one area until they have been sufficiently cut. Move to the next section and repeat the procedure until the entire length of the fence has been weeded.